Posted
by
timothy
on Tuesday September 11, 2012 @01:30PM
from the that-is-awesome dept.

RocketAcademy writes "Spaceweather.com reports an explosion on Jupiter, which was detected by two amateur astronomers. According to Spaceweather.com, the event occurred at 11:35 Universal Time on September 10. Dan Peterson of Racine, Wisconsin, observing through a 12-inch Meade telescope, observed a white flash lasting for 1.5-2 seconds. George Hall of Dallas, Texas was capturing a video of Jupiter at the time, which also captured the event. It's believed that the explosion was due to a comet or small asteroid collision. Similar events were observed in the past, in June and August 2010."

SL-9 was a farside impact. This, apparently, was a nearside (not much detail in the video). We should be worried, it could easily, since it obviously came from within Jupiter's orbit, have intersected with Earth. Anybody who has access to the object's orbital parameters which show that this would have been with 100% certainty, impossible, please feel free to call me a paranoid freak at this point; but we are overdue an ELE (Extinction Level Event) by about 15 million years (I keep reading around the science journals about ELEs happening about every 50 million years, the last one was what? 65 million years ago (the K-T Event)?

Why bother worrying about it?
While I agree that we should be looking for these things to prevent the entire planet from getting sterlized in a single blinding flash of light, why worry about it?
Either its going to hit in your lifetime, or its not. Until one is found you can do something about, there's no point in worrying about it, since the one we dont see coming we cant stop. Dead is dead, learn to enjoy life while you have it and stopy worrying about ELE events that are 'overdue'.

Wouldn't it just be a big randomizer of orbital paths? Why does it make kicking stuff away from usmore likely than kicking stuff towards us? I'm not saying it isn't (a big cleaner), just curiousabout the logic.

Because it is so big it can eject objects out of the solar system. And while it could easily direct an object towards the inner solar system, after billions of years the ones that it has ejected have decreased the total number enough that the inner solar system is a safe place.

He wasn't talking about statistics. He was talking about periodicity which is something that happens, you know, periodically. If there is some astronomical event (who knows, maybe it is Nemesis, maybe it is some sort of conjunction event) that tends to hurl more than the normal number of Oort cloud objects towards the inner solar system every 50 million years then yes, we are overdue. However that may be because we just didn't get hit this time and it will be another 35 million years before "the event" (wha

Why would someone who actually knew anything about orbital mechanics require 100% certainty to feel safe? Even Apophis, an object known to actually have a pretty good chance of hitting earth as such things go was estimated at 1 in 250,000 a few years ago. The odds of some random object disturbed by Jupiter hitting earth is going to be vastly lower.

Fund more telescopes for NEO (and other object) discovery and tracking. We have a network of telescopes doing this, but it is woefully inadequate for searching the skies sufficiently thoroughly. Early detection of potential impactors is the only chance we have of saving ourselves if/when the Big One comes. And it's only an "if" because it might not happen for many millions of years and who knows if our ancestors will be around then.

We should also be funding the development of the actual capability to deflect one. A gravity tractor craft is actually a pretty simple concept and achievable with todays tech given sufficient lead time, but I don't think we should risk the extra time it takes to go from concept to implementation once we do find one.

The main thing is more detection and tracking, though, because the lead time is essential. This should be considered a major defense priority. But it seems to be hard for people to take it seriously enough, because nobody can say if it will happen in any of our lifetime's.

Of course there's also the remote chance that an long-period comet hits us from the direction of the sun and we end up with basically no warning even with a ridiculously extensive discovery effort. In that case it's que sera sera.

And it's only an "if" because it might not happen for many millions of years and who knows if our ancestors will be around then.

Ancestors? My grandparents are long dead, and I'd be rather startled if my parents were to live for millions of years. If they're going to do that, I'd hope that they'd do so in good health; getting massively old while being in pain from aging would be horrible. Maybe medicine will allow this to happen, but it's rather far into the realm of science fiction at this point...

The main thing is more detection and tracking, though, because the lead time is essential. This should be considered a major defense priority.

If the chances are one in millions, then no, it shouldn't be. Even a "city-killer" will likely end up doing no or little damage unless it actually strikes near a city (improbable). I approve of a token effort that ramps up along with civilization, but there are higher priority things to worry about, like extreme solar flare events.

If the chances are one in millions, then no, it shouldn't be. Even a "city-killer"

"Even"? Objects like that are common. Apophis alone has more than one-in-a-million odds as currently estimated, and the estimated 500MT impact would be over 10,000 times larger than "city killer". There are plenty of objects out there of sufficient size where it's a global extinction event wherever they hit. We just don't know where they are, or if their orbits are such that they threaten us.

You can't just look at the odds,. You also have to look at the impact. The die has already been cast. There ar

The "even" refers to the impact, not the number, as "city killers" were used as the scary threat. They aren't scary. Maybe if they were landing on the order of once a year instead of something like every 100.

You can't just look at the odds,. You also have to look at the impact.

Yes, that's what I did.

while the odds of an impact in any given year are terribly low, we don't know if that means we're not going to see one for a million years, or if we're going to get hit and then not see one for a million years.

In other words, probability is random. Thanks for the update.

A token effort is a useless effort.

No, it isn't. By token I mean as a percentage of our resources. It really depends on how much bang you can get for the buck. As it is, even finding 1% of the threats is better than nothing and not useless.

And what does the ramping up of civilization have to do with it? We're just as screwed regardless of our civilization level. The relevant benchmarks are 1) are we capable of detecting them and 2) are we capable of doing something about it, and we're past both.

The "even" refers to the impact, not the number, as "city killers" were used as the scary threat. They aren't scary.

So because the GGP or whoever that didn't even know what they were talking about said that, your risk analysis is limited to those types of events despite the probabilities you used not even lining up? Fine, whatever. Now think beyond that. Think about the actual problem.

In other words, probability is random. Thanks for the update.

No, in other words, instead of relying on the odds that the cards turned down are favorable to us, we should actually try to look at the cards and see what the reality is.

As it is, even finding 1% of the threats is better than nothing and not useless.

So because the GGP or whoever that didn't even know what they were talking about said that, your risk analysis is limited to those types of events despite the probabilities you used not even lining up?

No, I responded to both arguments, the more frequent "city killers" that we see, and the once-in-tens-of-millions-of-years extinction events that we see.

No, in other words, instead of relying on the odds that the cards turned down are favorable to us, we should actually try to look at the cards and see what the reality is.

We have, and the odds are extremely low, so low that we have bigger things to prioritize.

But hey if you just meant "token" as a % of resources, then a fully-funded, vastly more effective effort would be such, like I was saying we could do that and address many other problems to.

The point is how much %, where you want a "fully-funded, vastly more effective effort". If it's cheap, then fine, but if it's extremely expensive, then it isn't.

And the simple facts are that if we decided to make these things priorities we could easily do both and many other things.

That's true of anything, and if you took that approach with everything you'd be back to square one due to lac

But the odds of some *specific* object disturbed by Jupiter hitting the Earth may be vastly *higher*.

The odds of such an object existing are low.

I mean at the end of the day Apophis may have a 100% chance of hitting us, or it might have a 0% chance of hitting us. We can only estimate based on what we know if its orbit. Without knowledge of a specific Jupiter-orbit object, we can only estimate based on the odds of potential disturbed orbits intersecting earth. This is how conditional probability works.

As far as the "maybes" go, NEOs are more likely to be dangerous than objects kicked around by Jupiter.

we've had more than 5 'city-killer' sized objects pass inside the Moon's orbit.

The math on the density of the asteroid field was done well before the Voyagers were conceived, and it was based on that math that they decided that no mitigation was necessary. So not literally zero, but rounding...:)

There's a good chance it passed through a keyhole [wikipedia.org] on an earlier pass near Jupiter, and hence struck the planet this time around. I would suspect a keyhole for Earth collision would be much smaller than one for a Jupiter collision. I'm not familiar with the math involved, but I would expect comets and asteroids to strike Jupiter relatively often; Earth, not so frequently.

Anybody who has access to the object's orbital parameters which show that this would have been with 100% certainty, impossible, please feel free to call me a paranoid freak at this point; but we are overdue an ELE (Extinction Level Event) by about 15 million years (I keep reading around the science journals about ELEs happening about every 50 million years, the last one was what? 65 million years ago (the K-T Event)?

"Overdue" is not a meaningful term in this case. We get about one large impact every 50 million years, but think about it statistically: a Poisson distribution with a mean of 1 has P(0) ~ 0.6, so even at 65 million years the odds are barely 50/50, and in any case, the events are uncorrelated so it doesn't matter how long ago the last one occurred.

When you wake up each morning the odds of you dying in an asteroid impact are the same: about one in a billion. Your odds of dying in a lightning strike or gett

To be fair, the frightening thing about astroids isn't that the probability: P(me dying in comet impact) is high. What's frightening is that the conditional probability: P(extinction of humanity | me dying in comet impact) is high.

We should be worried, it could easily, since it obviously came from within Jupiter's orbit, have intersected with Earth.

And?

but we are overdue an ELE (Extinction Level Event) by about 15 million years

So ELE events are extremely uncommon?

So why should we be concerned merely because an object, which has roughly 90% of the mass of the Solar System outside of the Sun, happens to get hit a lot by asteroids and comets? That huge mass is one of the reasons it gets hit so much. The other is the greater number of objects around Jupiter's orbit.

I find this more than a little disturbing. I remember when Comet Shoemaker-Levy hit Jupiter and astronomers were saying that the impact was a 'once in a lifetime' or 'once in a century' event. Just a couple of years ago other scars from an impact that wasn't witnessed (possibly far side) showed up, and now we have another. Sure, it might be a statistical fluke and there may not be another impact for 500 years, but it seems to me as though estimates of the amount of material wandering around the inner solar system might be quite low.

I seem to remember reading somewhere that Earth's relationship with Jupiter isn't always so amicable. Granted without it there probably wouldn't be life on Earth, but, if I recall correctly, objects that Jupiter doesn't swallowed up completely stood a reasonable chance of being deflected in the direction of the inner planets. Something of a devil in disguise!

That was my first thought also. But, following a link in the talkbacks to this http://spaceweather.com/archive.php?view=1&day=11&month=09&year=2012 [spaceweather.com] There is the comment that another astronomer, Dan Peterson (not the one who took the video), said the blast only lasted 1.5 to 2 seconds. This is very different from the famous comet smash of 1993 when the marks on the visible part of Jupiter lasted a long time while Jupiter rotated around.

I'll get out my 18" f/4.5 Obsession tonight and see if I can spot the scars.The last time this happened, there were black holes in Jupiter's clouds that persisted for several weeks.Unlike the last time this happened, its perfectly clear here in the Carolinas!Amateur Astronomers FTW!

Out of curiosity what do decent telescopes run and where does one buy them? I have a crappy 6" tasco one from when I was a kid that works well for looking at the moon, and limited planet viewing but sucks for everything else.

There's no simple answer to that question. What constitutes a "decent" scope? Weeelll..

A couple of things to know:
* Aperture (thus ability to gather light) is more important than magnification.
* There are essentially 3 kinds of scopes:
1) Refractor (classic design)
2) Newtonian reflector (more affordable). Newtonians are generally less money and give you more bang for the buck, and Dobsonian Newtonians are even better bargains, though a dob can't track objects as they can't use an equatorial mount. I have an 8" dob, and a small 80mm refractor, but what I'd really like is a
3) Cassegrain: , which is like an optically "folded" newtonian - they're small, light, and powerful, but not as cheap as newtonians.
You can look here for starters: http://www.telescope.com/ [telescope.com] (Orion)

Point taken. I've been out of the game for a while. Light pollution in my neighborhood is so bad I've taken a hiatus from stargazing.
BTW, I forgot to mention some ballpark prices, but I would venture that a worthwhile beginner's scope could run anywhere from between maybe $200 or $300 to $600 or more, but even that's highly subjective. Then of course, there are the accessories, like add'l eyepieces, which can raise expenditures significantly. Like any good hobby, you can sink more money into it than yo

My 18" Obsession has both Argo-Navis DSC and Servo-Cat Drives, so it can both go-to and track.It costs almost as much for the computer and drives as the rest of the scope =-)I learned my way around the skies star hopping with a 4.5" and 10" dob (which I still have). But it is sure nice to be able to dial in an object, hit go to, observe it for a while, go drink some coffee/tea, come back, and still have the object in the EP.

3) Cassegrain: , which is like an optically "folded" newtonian - they're small, light, and powerful, but not as cheap as newtonians.

As the owner of a Celestron 11" SCT, I'd say the main advantage is the size. Weight isn't dominated so much by the tube, but by the optics, and a SCT has more optics. Also, a lot of SCTs use fork mounts which can't be easily removed from the tube. So even if the body was lighter, the actual thing you have to pick up and lug around is significantly heavier than an equivalent Newton.

But if size matters, it's definitely the way to go. There's no way I'd get even an 8" Newton into my two-door Toyota Echo.

I'll second the Orion recommendation - good scopes and very good customer service.For $500, you can get a nice 8" dob, a couple of good eyepieces, a barlow, some charts, and get a nice start to the skies.